1. Field of the Invention
The present invention relates to an RFID reader and, more particularly, to an RFID reader having a multi-dimensional antenna array.
2. Description of Related Art
Products related to RFID systems have gradually been used in the industry, military and people's livelihood applications such as commodities barcode, logistics management, consumer electronic products, biomedical sensing, machine assembly, and so on. The RFID technology will certainly have a revolutionary influence to people lives in the future. Although the principle of this technology was proposed by Maxwell in the mid 19th century and has been developed for over one hundred years to come to maturity, its related applications have come into notice only recently. The reason why the RFID technology develops vigorously is that a all-new application is proposed in addition to the maturity of fabrication and design. For example, in the disclosure of TW Pat. No. TW565,802 “an object tracking and management system and method making use of RFID tags,” the RFID technology is applied to object tracking and management.
As shown in FIG. 1, a conventional RFID reader comprises an emission module 11, a signal receiving module 13, a resonator 15 and a microprocessor module 17. The emission module 11 is composed of a stabilized oscillation source circuit 101 and a power amplifier 103. The primary function of the emission module 11 is to provide a carrier frequency signal for the resonator 15. The resonator 15 is composed of an antenna 105 (or coil) and a capacitor 107, and is used to produce a time-varying EM field for providing an induction voltage for an RFID tag device 63. When the RFID tag device 63 gets a sufficient operation voltage, its internal ID code will be transmitted back to the RFID reader through EM induction. The signal receiving module 13 is composed of a Envelope detector 109 and an appropriate filtering and amplification circuit 111. The signal receiving module 13 is used to demodulate the ID code and restore it to a digital signal of logic level “0” or “1”. This restored digital signal will be processed by the microprocessor module 17. The microprocessor module 17 is a control center of the whole RFID reader, and is used for related control of recording, determination, decryption and different applications.
In the above conventional RFID system, the resonator 15 uses the single antenna 105 to match several RFID tag devices for one (the RFID reader) to many (the RFID tag devices) application. The primary drawback is that the RFID reader can only passively await the approach of an RFID tag device within the emission EM field range of this antenna.
Accordingly, the present invention aims to propose an RFID reader having a multi-dimensional antenna array to solve the above problems in the prior art.